1. Field of the Invention
This invention relates generally to devices for signaling to the driver of a vehicle when the driver has depressed the accelerator of the vehicle at or beyond a selected rate of depression that causes fuel efficiency to fall below a selected adjustable level. More particularly the invention relates to a pneumatic device that is inserted between a vehicle accelerator pedal and the floor beneath the pedal and emits an audible signal when the selected rate of depression is exceeded.
2. Description of the Related Art
The efficient use of vehicle fuels continues to have increasing importance to both vehicle owners and the entire nation. More efficient use of fuels results in lower costs to operators and owners of motor vehicles. The prior technology has recognized that fuel economy is a decreasing function of vehicle acceleration. As a result, many devices have been proposed for improving fuel efficiency by signaling to a driver that the driver has operated an acceleration control pedal in a manner that will cause a reduction of fuel efficiency below a selected efficiency limit.
The pressure in the intake manifold of an internal combustion engine (often referred to as vacuum) has been recognized as an indicator of the amount of acceleration that a driver is seeking when the driver depresses the vehicle's accelerator. As a result, several devices have been proposed for sensing intake manifold pressure and taking some action when the accelerator has been depressed sufficiently far that fuel economy has been reduced below a desired limit. The action taken by some devices is to reduce the acceleration. That action, however, poses a risk if high acceleration is needed to avoid a safety threat. Other devices do not affect vehicle operation and instead permit the driver to maintain control but signal to a driver that fuel efficiency has declined below a selected limit. By only signaling to a driver, the device allows the driver to either reduce acceleration or override the signal and maintain the acceleration chosen by the driver. Examples of such devices are U.S. Pat. Nos. 2,825,418; 3,961,598; and 4,077,370.
One problem with devices that sense intake manifold pressure is that they require connection to the intake manifold. For an original equipment manufacturer, that can be done but increases the cost of vehicle manufacture. Installing an aftermarket device of this type is beyond the capability of an ordinary driver and would require a substantial amount of time for a skilled mechanic and therefore a substantial investment by the vehicle's owner.
The difficulty of making a connection to the intake manifold is avoided by a signaling device of the type shown in U.S. Pat. No. 3,952,688. That device is a cylindrical bellows that is attached to the underside of a vehicle accelerator pedal by a band extending over the pedal. A whistle audibly signals a driver when the accelerator is depressed at a sufficient rate to increase the internal air pressure enough to actuate the whistle. Although the device shown in the patent offers desirable features, it has deficiencies that have reduced the practicality of its adoption.
One deficiency is that the device of the patent is susceptible to being moved out of position because of the combination of the manner it is mounted in place and its configuration. Because the device is held on the accelerator pedal only by a band extending over the top of the pedal, the device can easily slide longitudinally along the pedal if a force is applied to it in the longitudinal direction of the pedal. Because the top and bottom of the device are parallel but an accelerator pedal is often at an angle to the floor, the bottom edge on one side of the device will first contact the floor beneath the pedal at the lowermost side of the bottom. Then, as the pedal is depressed further, the bottom of the device will pivot around the point of first contact until the entire bottom contacts the floor. This pivoting movement will apply to the top of the device a force that has a component longitudinally along the pedal. Therefore, each depression of the pedal can result in a very small longitudinal movement along the pedal. The cumulative effect of many depressions soon causes a noticeable longitudinal movement of the device along the pedal. Another deficiency exists if the undepressed pedal is above the underlying floor a distance greater than the height of the device causing the bottom of the patented device to be spaced above the floor. The result is that the pedal can be partially depressed without compressing the device thereby rendering the device inoperable for an initial interval of pedal depression.
Other deficiencies result from securing the device to the pedal by means of the band going across the top of the pedal. One problem is that the bellows device can easily be accidentally kicked laterally out from under the pedal by a driver's foot and rotated to one side or the other of the pedal. To safely replace it, the driver would be required to stop the vehicle. Unfortunately, some drivers would be likely to try to kick it back into place while driving thereby creating a safety hazard.
Two of the more significant problems with the device of the patent arise from its use of several adjacent pleats around its perimeter that together form a bellows arrangement. For any device that is used in connection with any control pedal for a vehicle, a designer must consider the potential consequences in the event that the device comes loose from its intended position and becomes lodged or otherwise located beneath one of the other control pedals. If that happens, the device should not cause a vehicle control problem. If the device of the patent was located beneath a control pedal in an orientation having its pleats extending between the pedal and the floor (i.e. 90° to its intended orientation), the corrugated configuration of the pleats would cause the device to apply a substantial force to a pedal that is being depressed thereby resisting its depression.
Another problem with a bellows arrangement arises because the pleats of a bellows lie one above the other. As such a bellows is compressed, the walls of the pleats move closer until they lie against each other when the bellows is fully compressed. With the bellows fully compressed, the thickness of each pleat wall adds to the thickness of the remaining pleat walls to sum to a minimum bellows height. The bellows can only compress until its pleat walls lie against each other. In the case of the patented device, this minimum height is approximately eight times the material thickness. This minimum bellows height imposes a limit on the amount of depression of the accelerator. While that is not a problem for most driving situations, in the event that a driver needs to have the highest possible acceleration in order to avoid an unexpected safety emergency, the bellows arrangement reduces the amount of accelerator depression available to the driver. Similarly, in the event that the device became positioned beneath another control pedal but in its proper orientation, it would impose the same pedal depression limitations.
It is therefore an object and feature of the invention to eliminate these deficiencies by providing a fuel efficiency signaling device that:                1. is quick and easy to install including requiring no disconnection of the linkage from the accelerator pedal to the engine's speed controlling device, such as the carburetor, fuel injection system or the speed control of an electrically powered vehicle, requiring no disconnection of a pedal pivot or any other structure and requires no connection to the accelerator pedal or linkage in order to be installed in its operable position;        2. can be manufactured in one or a very few standardized models and yet fits and operates properly and safely in the wide variety of accelerator configurations that are used in commercially available vehicles;        3. poses considerably less restraint upon the depression of control pedals in the event that the device becomes displaced from its intended position and becomes positioned beneath another pedal, regardless of its orientation;        4. does not have adjacent pleats that are characteristic of a bellows and that increase the minimum thickness of compression of the device; and        5. is more securely held in place against accidental lateral displacement and against longitudinal displacement to minimize the risk of the device being dislodged.        
Further objects and features of the invention are described in the subsequent Detailed Description of The Invention.